Ubuntu 22.04 LTS / 24.04 LTS / 25.10 : libpng vulnerabilities (USN-8251-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8251-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('compat.inc');

if (description)
{
  script_id(314216);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/05/14");

  script_cve_id("CVE-2026-33416", "CVE-2026-33636", "CVE-2026-34757");
  script_xref(name:"USN", value:"8251-1");

  script_name(english:"Ubuntu 22.04 LTS / 24.04 LTS / 25.10 : libpng vulnerabilities (USN-8251-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 22.04 LTS / 24.04 LTS / 25.10 host has packages installed that are affected by multiple
vulnerabilities as referenced in the USN-8251-1 advisory.

    It was discovered that libpng incorrectly handled memory when processing certain PNG files. If a user or
    automated system were tricked into opening a specially crafted PNG file, an attacker could use this issue
    to cause libpng to crash, resulting in a denial of service, or possibly execute arbitrary code.
    (CVE-2026-33416)

    It was discovered that libpng incorrectly handled expanding 8-bit paletted rows to RGB or RGBA on ARM
    processors. If a user or automated system were tricked into opening a specially crafted PNG file, an
    attacker could use this issue to cause libpng to crash, resulting in a denial of service, or possibly
    execute arbitrary code. (CVE-2026-33636)

    It was discovered that libpng incorrectly handled certain setter APIs. An attacker could possibly use this
    issue to obtain sensitive information. (CVE-2026-34757)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/notices/USN-8251-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-33636");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2026-34757");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/03/10");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/05/07");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/05/11");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:22.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:24.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:25.10");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpng-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpng-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpng16-16");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpng16-16t64");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Ubuntu Local Security Checks");

  script_copyright(english:"Ubuntu Security Notice (C) 2026 Canonical, Inc. / NASL script (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('22.04' >< os_release || '24.04' >< os_release || '25.10' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 22.04 / 24.04 / 25.10', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Ubuntu', cpu);

var pkgs = [
    {'osver': '22.04', 'pkgname': 'libpng-dev', 'pkgver': '1.6.37-3ubuntu0.5'},
    {'osver': '22.04', 'pkgname': 'libpng-tools', 'pkgver': '1.6.37-3ubuntu0.5'},
    {'osver': '22.04', 'pkgname': 'libpng16-16', 'pkgver': '1.6.37-3ubuntu0.5'},
    {'osver': '24.04', 'pkgname': 'libpng-dev', 'pkgver': '1.6.43-5ubuntu0.6'},
    {'osver': '24.04', 'pkgname': 'libpng-tools', 'pkgver': '1.6.43-5ubuntu0.6'},
    {'osver': '24.04', 'pkgname': 'libpng16-16t64', 'pkgver': '1.6.43-5ubuntu0.6'},
    {'osver': '25.10', 'pkgname': 'libpng-dev', 'pkgver': '1.6.50-1ubuntu0.5'},
    {'osver': '25.10', 'pkgname': 'libpng-tools', 'pkgver': '1.6.50-1ubuntu0.5'},
    {'osver': '25.10', 'pkgname': 'libpng16-16t64', 'pkgver': '1.6.50-1ubuntu0.5'}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var osver = NULL;
  var pkgname = NULL;
  var pkgver = NULL;
  if (!empty_or_null(package_array['osver'])) osver = package_array['osver'];
  if (!empty_or_null(package_array['pkgname'])) pkgname = package_array['pkgname'];
  if (!empty_or_null(package_array['pkgver'])) pkgver = package_array['pkgver'];
  if (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  if (osver && pkgname && pkgver) {
    if (deb_check(release:osver, prefix:pkgname, reference:pkgver, cves:cves)) flag++;
  }
}

if (flag)
{
  var extra = '';
  extra += ubuntu_report_get();
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'libpng-dev / libpng-tools / libpng16-16 / libpng16-16t64');
}